Master Exam Array question

[AustinRay Lee]

Can someone explain the answer to this problem, master exam says that answer C below "is wrong because C tries to assign a two-dimensional array where a one-dimensional array is expected." I can see that b is a two-dimensional array, but it looks like b2 is four-dimensional array. So I would expect the answer to say "C is wrong because C tries to assign a two-dimensional array where a four-dimensional array is expected." Or why is b2 considered a one-dimensional array when it has 4 []'s.
public class Test{
public static void main(String [] args){
short [][] b = new short [4] [4];
short [][]big = new short [2][2];
short b3 = 8;
short b2 [][][][] = new short [2][3][2][2];
// insert code here
}
}
A b2[1][1] = big;
B b[1][0] = b3;
C b2[0][1][1] = b:

[Stan James]

Let's start simple and build up ...

int[]a = new int[2];        // 1d array of int
a[1] = 5;                   // each slot can be assigned an int
int[][] b = new int[2][2];  // 2d array
b[1][1] = 4;                // each slot in 2nd dim is an int
b[1] = a;                   // each slot in 1st dim is a 1d array
int[][][]c = new int[2][2][2]; // 3d array
c[1][1][1] = 3;             // each slot in 3rd dim is an int
c[1][1] = a;                // each slot in 2nd dim is a 1d array
c[1] = b;                   // each slot in 1st dim is a 2d array
int[][][][]d = new int[2][2][2][2]; // 4d array as in question
d[1][1][1][1] = 2;
d[1][1][1] = a;
d[1][1] = b;
d[1] = c;

Whew. Looks like what you can put into any slot is enough dimensions to fill out the original declaration. In "a[1]" that means no more dimensions, only an int. In d[1][1][1] as in your question, only one more dimension.